Oh dear, I do feel for you..nothing worse than having to undo millions of stitches.....don't dwell on it, it will just become more upsetting...just jump into the unpicking with gritted teeth and your favourite music playing!
I once put my iron, sole down onto the carpet in my sewing room forgetting that it was still switched on. Came back into the room a few minutes later finding the carpet scorched and the place smelling foul!